Flexible robot arm

ABSTRACT

This invention relates to a flexible robot arm comprising a plurality of disc-shaped elements arranged in a series so as to consist of a flexible arm, both surfaces of each of the elements being formed in convex having an arched opposed single curve so as to form contact surfaces, and a plurality of wire-like actuating devices for allowing the flexible arm to curve or bend in a desired direction. The flexible robot arm of this invention is directed to make motors for driving the actuating devices compact in size and light in weight and also a drive unit section compact in size and light in weight. The flexible robot arm includes two drive units each interconnected to the proximal ends of respective pairs of actuating devices (e.g. 3a and 3c, and 3b and 3d) disposed oppositely to each other on the diagonal and driven through rotary members (5a, 5b, 9a, 9b or 12a, 12b, 12c, 12d) each being rotated by one of the motors (8a, 8 b) in both the clockwise and the anti-clockwise directions.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a flexible robot arm which comprises aplurality of elements arranged in a series so as to engage with eachother at their respective contact surfaces each formed in an archedopposed single-curve and actuating devices arranged to operate betweenthe elements adjacent to each other or to actuate the elements forgenerating and/or transmitting power, thereby supporting and/ormanipulating a tool or the like connected to the leading end of therobot arm.

TECHNICAL BACKGROUND OF THE INVENTION

Heretofore, this kind of a flexible robot arm has been known asdisclosed in Japanese Patent Publication No. Sho 59-21756 (U.S. Pat. No.4,393,728).

The prior art flexible robot arm disclosed in the publication isprovided with a plurality of disc-shaped elements each of which both thetop and the bottom surfaces thereof having arched opposed double-curveare formed as contact surfaces, respectively, and at a peripheralportion of each disc-shaped element, a plurality of actuating devices(for example, four devices) each comprising a length of cable, etc., areallowed to penetrate the element at plural spots (for example, fourspots) spaced apart from one another at an equal distance in theperipheral direction of the disc-shaped element. Respective leading endsof the actuating devices are independently connected to an elementarranged at the most distal end, while respective base ends of theactuating devices are connected to a plurality of drive units (forexample, four unit) mounted independently of one another. Each of thedrive units serves as selectively drawing or loosening the actuatingdevice interrelating to each other. Such as, for example, a drum unitallowed to bidirectionally rotate by means of a motor, a hydrauliccylinder unit allowed to extrude and retract, etc. are preferably used.

Such a prior art flexible robot arm as described above is adapted to beconstructed so as to bend or move in a direction such that at least oneof the actuating device is drawn.

Further, as is clearly understood from the foregoing description, in theaforesaid prior art flexible robot arm, the actuating devices arerespectively actuated by the drive units mounted independently of oneanother. Accordingly, when a moving stroke of each actuating device isdefined as L, the maximum extruding or retracting length is required atmore than 2L in case, for example, of the hydraulic cylinder unit as adrive unit. Therefore, a drive unit section of the flexible robot armwhere the same numbers of hydraulic cylinder units as those of actuatingdevices are mounted thereat requires a large space and hence becomes aremarkably heavy weight. In particular, in order to deal with works tobe performed at an area where is further away and extends in widerrange, there is provided such a flexible robot arm as connecting aplurality of flexible arms in a series through their respective driveunits. In this flexible robot arm, the durability of itself remarkablydeteriorate because of a heavy weight of each of the drive units whichare respectively connected between the respective flexible arms adjacentto each other.

Further, since a space occupied by the drive section becomes large asmentioned above, the flexible robot arm must be formed in a big size. Asa result, it has a further disadvantage such that the work site wherethe big sized flexible robot arm is used must be limited.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-mentionedcircumstances in the prior art, and has for its aims to provide aflexible robot arm in which a motor for driving each of actuatingdevices can be made in a light weight and a small capacity, andtherefore a drive section thereof can be made in a small size and alight weight.

In order to achieve the above-mentioned aim, according to a first aspectof the present invention, there is provided a flexible robot armcomprising: a plurality of disc-shaped elements arranged in a series andeach of which both surfaces having an arched opposed single-curve,respectively, being served as contact surfaces; a plurality of wire-likeactuating devices which penetrates the disc-shaped elements at pluralspots where are positioned at a peripheral portion of each element andare spaced apart from one another at an equal distance and which areconnected at their respective leading ends to the most distal endelement; and a plurality of drive units mounted in a drive section andconnected to respective proximal ends of the wire-like actuatingdevices, respectively, for selectively drawing and loosening thewire-like actuating devices to curve and bend or move a robot armconsisting the elements, the flexible robot arm being characterized inthat the drive units comprises two drive units mounted in the drivesection so as not to interfere with each other, each of the drive unitsbeing connected to respective proximal ends of a pair of wire-likeactuating devices out of the plurality of wire-like actuating deviceswhich are oppositely disposed on the diagonal line and being derivedthrough a rotatable body rotated by means of a motor in the clockwiseand the anti-clockwise directions.

According to a second aspect of the present invention, there is provideda flexible robot arm, characterized in that each of the drive units asdescribed in the first aspect comprises a pair of rack members mountedmovably so as to be opposite to each other and to be connected to therespective proximal ends of the pair of wire-like actuating devices,respectively, and a pinion disposed between the pair of rack members soas to engage simultaneously with both the rack members and allowed torotate by means of a motor in the clockwise and the anti-clockwisedirections.

According to a third aspect of the present invention, there is provideda flexible robot arm, characterized in that each of the drive units asdescribed in the first aspect comprises a pulley allowed to rotate bymeans of a motor in the clockwise and the anti-clockwise directions, anda belt wound around the pulley so as not to cause any slip on the pulleyand connected at both ends thereof to the respective proximal ends ofthe pair of wire-like actuating devices, respectively.

According to a fourth aspect of the present invention, there is provideda flexible robot arm, characterized in that each of the drive units asdescribed in the first aspect comprises a pair of slidable membersconnected to the respective proximal ends of the pair of wire-likeactuating devices, respectively, and a pair of threaded arms allowed toengage with the pair of slidable members, respectively, and to rotatethrough a gear train by means of a motor, wherein the pair of slidablemembers causes them to slide in the opposite directions to each otherwhen the threaded arms are rotated by the motor.

The above and many other advantages, features and additional objects ofthe present invention will become manifest to those versed in the artupon making reference to the following detailed description andaccompanying drawings in which preferred structural embodimentsincorporating the principles of the present invention are shown by wayof illustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view showing the structure of the principalpart in a first embodiment as a flexible robot arm of the presentinvention;

FIG. 2 is an explanatory view showing the structure of the principalpart in a second embodiment as a flexible robot arm of the presentinvention; and

FIGS. 3A and 3B are explanatory views showing structures of theprincipal parts in a third embodiments of the present invention as aflexible robot arm.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, the present invention is explained in more detail withreference to the accompanying drawings.

In the first place, a first embodiment of the present invention isexplained with relation to FIG. 1.

In FIG. 1, reference numeral 1 represents a base plate fixedly securedto a framework, not shown, of the embodiment. On the base plate 1, aplurality of disc-shaped elements 2a, 2b, 2c, . . . 2n each being formedwith convex contact surfaces at both the top and the bottom surfacesthereof are pilled in a series. In four spots positioned at a peripheralportion of each element and spaced at an equal distance in theperipheral direction of each element apart from one another, actuatingdevices consisting of wires 3a, 3b, 3c and 3d are respectivelypenetrated, in turn, in the clockwise or the anti-clockwise direction.Further, respective leading ends of the wires are connected to theelement 2n disposed at the most distal end portion. The respectiveproximal ends of the actuating devices 3a to 3d are connected to rackmembers 4a, 4b, 4c and 4d, respectively, forming two pairs of driveunits after penetrating the base plate 1. Out of these rack members 4ato 4d, respective two pairs thereof 4a, 4c and 4b, 4d connected twopairs of actuating devices 3a, 3c and 3b, 3d, respectively, in whicheach pair of actuating devices are positioned oppositely to each otheron the diagonal line, are disposed oppositely to each other and shiftedin position to each other in the longitudinal direction thereof so asnot to cause any interference with each other. In addition, pinions 5a,5b are mounted so as to engage with the rack members of the respectivepairs thereof, respectively. These pinions 5a, 5b are adapted to shifttheir respective phases at 90 degrees to each other with respect to thedirections of their respective faces, and further each of the pinions issubjected to a reference tensioning force F by a loading member 7 suchas, for example, a compression spring through a support member 60a or60b and an intermediate plate member 6 bearing the support member 60a or60b. A hydraulic cylinder unit is preferably used also as the loadingmember 7.

To their respective rotary shafts 50a, 50b of the pinion 5a, 5b isconnected motors 8a, 8b, respectively. Further, the rack members 4a to4d are slidably supported to guide members, not shown, respectively.

In such a first embodiment as constructed above, all of the fouractuating devices 3a to 3d are subjected to the action of even referencetensioning force by means of the loading member 7. Thus, a flexible armof this first embodiment consisting of the plurality of disc-shapedelements 2a, 2b, 2c, . . . 2n has such an attitude as extending at rightangles to the base plate 1.

Under the condition, when one of the pinions 5a is rotated in theclockwise direction by means of the motor 8a, one rack member 4a of thepair of rack members 4a, 4c allowed to engage with the pinion 5a ismoved upwards, while another rack member 4c is moved downwards. As aresult, a tension acted on the actuating device 3a connected to theupwardly moved rack member 4a is reduced less than the referencetensioning force, while that acted on the actuating device 3c connectedto the downwardly moved rack member 4c is increased more than thereference tensioning force. Accordingly, the flexible arm is subjectedto such a deformation as curved or bent in the direction where thetension is increased as shown in FIG. 1.

At that time, a force by which the actuating device 3a is loosened andthe other force by which the actuating device 3c is drawn are equal toeach other, but their respective operating directions are different fromeach other. Further, at that time, the motor 8a driving the pinion 5a ispermitted to output such a force as required to curve or bend theflexible arm by the action of the two actuating devices 3a, 3c, becausethe reference tensioning force is added by the loading member 7.

On the other hand, by the operation in a similar manner as describedabove, the flexible arm is subjected to the deformation as curved orbent on the different direction according to a degree of rotating angleof the pinion 5b when the other pinion 5b is rotated by means of theother motor 8b.

And furthermore, the flexible arm can be curved or bent in a desireddirection by allowing both the motors 8a, 8b to control their respectiverotations simultaneously with each other.

In the next place, a second embodiment of the present invention isexplained in relation to FIG. 2. Hereupon, in FIG. 2, construction partsrepresented by the same reference numerals and the same referencesymbols as those shown in FIG. 1 are free from explaining because theyare the same parts and have the same operating functions as those in thefirst embodiment.

In FIG. 2, two pairs of drive units for driving two pairs of actuatingdevices 3a, 3c and 3b, 3d, respectively, comprises two pulleys 9a, 9bdisposed under the base plate 1 in such a positioning relationship asspaced apart from each other in the vertical direction, and connectingmembers 30a and 30b such as, for example, belts wound around the pulleys9a, 9b, respectively, so as not to cause any slippage. The pulleys 9a,9b are so mounted as to be rotatable by means of motors 8a, 8b in theclockwise direction and the anti-clockwise direction, while respectiveboth ends of the belts 30a, 30b are connected to the respective proximalends of the actuating devices 3a, 3c, respectively.

Thus, when the pulley 9a and/or the pulley 9b are/is caused to rotate inthe clockwise or the anti-clockwise direction, the actuating device 3aor 3c and/or the other actuating device 3b or 3d are/is drawn orloosened so as to curve or bend the flexible arm in a desired direction.

In addition, hereinafter, a third embodiment of the present invention isexplained with reference to FIGS. 3A and 3B. Hereupon, in FIGS. 3A and3B, as is similar to the case of the above-described second embodiment,construction parts represented by the same reference numerals and thesame reference symbols as those shown in FIG. 1 are free from explainingbecause they are the same parts and have the same operating functions asthose in the first embodiment.

As is clear from FIG. 3A, respective proximal ends of a pair ofactuating devices 3a, 3c are fixedly connected to slidable members 10a,10c, respectively, which are beared to a framework of a flexible robotarm in the third embodiment so as to be allowed to be slidable in thevertical direction. These slidable members 10a, 10c are permitted toengage by the interposition of a gear train 11a with two threaded arms12a, 12c, respectively, upstanding vertically and rotatably by means ofa motor 8a. In the third embodiment shown in FIG. 3A, the two threadedarms 12a, 12b are allowed to rotate by the motor 8a in the samedirection simultaneously with each other because of the interposition ofthe gear train 11a. Accordingly, in order to cause the sliding members10a, 10c to slidingly move in the opposite directions to each other soas to draw either one of the actuating devices 3a, 3c and, on the otherhand, to loosen the other actuating device, it is necessary to formeither one of threads of the threaded arms 12a, 12b into a reversedthread.

However, it is not shown in the drawings, in case of forming theirrespective threads of both the threaded arms 12a, 12b into the identicalthread with each other, a power transmitting section such as, forexample, the gear train may be constructed such that rotation from themotor 8a is transmitted so as to rotate either one of the threaded armsreversely to the other threaded arm.

FIG. 3A and 3B shows another drive unit for driving another pair of theactuating devices 3b, 3c. This drive unit has the same structure and thesame operating function as those in the drive unit shown in FIG. 3A.Therefore, the explanation thereof is omitted.

Hereupon, in FIGS. 3A and 3B, it is a matter of course that theabove-described pairs of slidable members 10a, 10c and 10b, 10c aremounted independently of one another so as not to cause any interferencewith one another upon their respective sliding movements.

While the invention has been particularly shown and described inreference to preferred embodiments thereof, it will be understood bythose skilled in the art that changes in form and details may be madetherein without departing from the spirit and scope of the invention.

What is claimed is:
 1. A flexible robot arm comprising:a plurality ofdisc-shaped elements arranged in a series and each of which bothsurfaces having an arched opposed single-curve, respectively, beingserved as contact surfaces; a plurality of wire-like actuating deviceswhich penetrate said disc-shaped elements at locations positioned at aperipheral portion of each element and spaced apart from one another ata substantially equal distance, said plurality of wire-like actuatingdevices being connected at their respective leading ends to the mostdistal end element; and a plurality of driving means mounted in a drivesection and connected to respective proximal ends of said wire-likeactuating devices, respectively, for selectively drawing and looseningsaid wire-like actuating devices to curve and bend or move a robot armhaving the elements, wherein said driving means comprises two driveunits mounted in the drive section so as avoid interference with eachother, each of said driving means being connected to respective proximalends of a pair of wire-like actuating devices out of said plurality ofwire-like actuating device which are oppositely disposed on the diagonalline and being driven through a rotatable body rotated by means of amotor in the clockwise and the counter-clockwise directions, whereineach of said driving means comprises a pair of rack members mountedmovably so as to be opposite to each other and to be directly connectedto the respective proximal ends of said pair of wire-like actuatingdevices, respectively, and a pinion disposed between said pair of rackmembers so as to engage simultaneously with both the rack members andallowed to rotate by means of a motor in the clockwise and thecounter-clockwise directions.